Biomechanical effects of gamma irradiation on fresh frozen allografts in vivo.

The effect of gamma irradiation on the mechanical properties of allograft in a rabbit model was examined. Tibial allografts were tested in torsion to failure to determine maximum torque and maximum stress. Statistically significant degradation in the torsional strength of irradiated tibias vs controls was demonstrated. Femoral allografts were orthotopically implanted into experimental rabbits and secured with an intramedullary pin. Rates of incorporation and failure patterns were significantly altered by irradiation. These data suggest that sterilization of fresh-frozen allografts with 2.5 Mrad or greater severely degrades the ability of the graft to resist torsion. The rate of incorporation of fresh-frozen allografts also may be dramatically decreased as a result of irradiation.